CV-halfshafts WARNING!

[Alec Pringle]

Good to hear that you are still in one piece, Howard . . . . sympathies in respect of the TR.

 

As a matter of interest, in view of previous comment, what rubber and shocks has the car been run on ?

 

Cheers,

 

Alec

[rcreweread]

I have been following this post closely, as I know I have some play in the splines of both driveshafts on my TR4A rebuild - my hubs feel OK with no discernible play but as they are separated from the car and their trailing arm, it is not possible to mount a wheel on them to test for play more easily - these hubs have not been on the road since at least the end of the 1970s, and I don't know the mileage they have done in their working life either, but fair to say that they have obviously not had the same use as items in use all their working lives . My dilemma is what to do next, bearing in mind that financial considerations are very relevant as well.

 

 

I think a fair conclusion would be not to use reconditioned hubs because of the danger of metal fatigue/cracking. New standard hubs from two well known suppliers are currently available at approx £300 and £288 each, representing a cost of £600 a pair. If we now consider driveshafts, the cheapest standard shafts ( Chinese manufacture?) I have found are £95 each, which I understand have a pretty short working life - from the same supplier, uprated ones are £199.50 each - Proptech do ones with a rislan coating on the splines at £144 each, and they have been regularly recommended on this forum.

So if we go for new hubs and Protech shafts, we are talking of an overall cost of about £900 - this is not a lot different from the uprated CV jointed shafts and hubs available from a number of suppliers - under this scenario, assuming one isn't a stickler for originality, which is the no brainer?

 

If the standard setup ( or as near as you can get to it) was noticeably cheaper, I agree there would be no reason and daft to ignore it, but as this isn't the case, surely it makes sense to seriously consider the modern upgrade, or am I missing something? I have to admit I am no nearer to knowing which way to jump and which ones/brand to go for.

 

Cheers

 

Confused Rich

 

PS Posted before I read of Howard's experience

Edited July 15, 2017 by rcreweread

[ike551]

Hi Alex

Rubber was changed from Goodyear ( about 9 years old ) to Vredestein in May just before the NLG went to Spa

 

Shocks are Gaz and have been for 12 years set fairly soft as I fell in love with the TR6 as a kid because it squatted when pulling away and changing gear

 

Thanks for concern

Regards

Howard

[astontr6]

I've seen the first hand detail of 4 hub breakages in the past 15 or so years.

 

One occurred soon after the car had suffered a puncture and whacked a kerb hard enough to shatter the alloy wheel on the n/s/r, which I think can be most likely attributed to that impact rather than its being fitted with tube shocks and 195 tyres.

 

The other three incidents did not seem to have been preceded by any impact situations, all three cars were fitted with tube shock conversions, two sported 195 and the third 205 rubber . . . . . there were other 'upgrades' involved but I can't recall all the chapter and verse.

 

In all four instances the car was two-up and loaded boot.

 

Cheers,

 

Alec

Alec,

 

Do you know exactly where they sheared off?

 

Bruce.

[Motorsport Mickey]

It happens to Stags as well, even though all Stag drivers have auditioned for "Driving Miss Daisy" there are reports of hub or stub axle failure

 

 

This Stag owner had a pair of "reconditioned" hubs fail within 12 months of each other.

 

I strongly recommend originals or reconditioned units are replaced with new hubs whichever driveshafts you pick to use with them.

 

Mick Richards

Edited July 15, 2017 by Motorsport Mickey

[Waldi]

Howard thanks for sharing your personal experience, technical preference and originality aspects are suddenly not inportant at all. Safety comes First.

 

Like many of us, I am prepared to buy new uprated or standard drive shafts, as long as it is a one time (fit & forget) exersize.

I have not read about one on this forum yet, but individual installations can be ok (like many old hubs and shafts by the way!).

I cannot imagine these items are sold by thousands, so with all issues reported on shafts from several suppliers, what to buy?

The "good" thing is that new items can have issues like too much play in the bearings, but do not fail catastrophic.

I think good after sales service is an important factor.

Waldi

[aardvark]

The racetoration (cosworth?) hubs are noted on their website as designed to eliminate the known weakness in the stub axles. Is this done via bigger diameter stub axles? Are these hubs the safe alternative to cv's then?

[stuart]

The Racetorations shafts are a totally different hub with a roller bearing. http://www.racetorations.co.uk/triumphs-c56/tr4a-c8/tr4a-axle-and-differential-c105/racetorations-fast-road-race-hub-and-competition-driveshaft-assembly-p243

Or use the ones I like that are pretty much the same from Dennis Vessey. http://www.vessey-classic-car-services.co.uk/triumph-tr-rear-hubs.htm#.WWtTg-mQzGg

With their shafts http://www.vessey-classic-car-services.co.uk/triumph-tr-rear-driveshafts.htm#.WWtTtOmQzGg

You wont break them and if you ever need to replace a bearing you can do it yourself.

I would use these over any other alternative, OK costly but money better spent than a lot of the other go fast bits that some people insist they want but will never need.

Stuart.

Edited July 16, 2017 by stuart

[astontr6]

I have followed this thread with interest and have resisted replying until now having been the victim of a broken rear of side shaft two days before the international weekend

I was alone in the car , the weekend before we had been to the Red Rose weekend ,driven just under 600miles , the last being the dash home at approx 200 motorway miles , loaded and two up

The Tr was parked up , on the following Wednesday Evening I was on my way to Luton Hoo via the M25 onto the M1 when my sat navy took me off the M1 at Hemel Hempstead because of traffic congestion

It was on the A414 slip road after a couple of stop/starts in heavy traffic that the tr wheel came adrift launching the car into the air as the inertia took me over the wheel and dumped me on the tarmac

I got out not really knowing what had happened until I saw my wheel behind me , as I was in a slip road for a motorway I was forced to accept a police recovery , they have cart blanc to remove a vehicle hazard as quick as possible without worrying about vehicle damage , on top of that it cost £200 to be taken to a garage 4 miles away , £150 of that was just for putting the car on the transporter

When I think of what could have been the previous weekend and moments before it is not an experience I wish to repeat

So I spent all day Saturday of the international researching drive shafts and hubs

My conclusion was that I never want to be in a position where my hubs could EVER come off again so I bought CV drive shafts

Clonks I can live with, it's called driving classic cars , but here it is I WILL LIVE or if you wish, not die with only three wheels on my TR

We have a car show this weekend and my wife refuses to drive the car with our granddaughter in it while I drive the Cadillac , so it's not going

The alternative is to sell the car and buy an MX5

Your life , your choice , my life my choice , lucky my interior is brown is all I can say

 

Howard Pryor

You know the car , Ferrari blue TR6 mildly tuned , driven like a sports car should be driven

Hi Howard

 

So glad you have lived to tell the tale - I can't imagine what injuries you suffered from this experience but hope you are now fully recovered and your car too is now properly repaired to your safety requirements.

 

Regards, Bruce Martin

Chiltern TRs

[Keith66]

 

Hi All

Reading recent posts and adding to my earlier post about “updates” to our cars, re the safety on modern cars and how much to try to transfer to our classics.

Two schools of thought really, change everything we technically can and make our cars as safe as possible. Technically I’m sure you could but you could but would need a rather large budget, we know what Eagle charge for doing that on an E type. Or we accept that on cars 40 to 55 years old the design simply won’t be as safe as modern equivalents and some stuff will need to be changed as it gets older just to try retain the original safety margins.

Which raises another question re Howards hub failure, (was it like the Stag type failure Mick posted pic’s of) and if so did it fail because of a previous impact causing damage, was it due to age related fatigue or are they such a poor design that will definitely fail at some point?

And the cause kind of dictates what we may want to do with the component. So in terms of possible damage probably replace with the same spec item after the impact, in terms of age, replace component at an approx. age (a la cambelts) or redesign and replace an inherently unsafe item with a new updated version.

I tend to go with the keep it more or less as it was designed unless it’s clear the original design was badly flawed. And its best to remember some updates can put more stress on components previously within design parameters, so most commonly more power and bigger tyres and wheels. Don’t forget no-one designing the TR IRS in what the early 60’s had even heard of a 206/60 let alone had any experience of them.

And bear in mind that even new car components fail too, because normally if someone designs something and then someone builds it something will fail somewhere along the line.

Things even fail on airliners in one of the most heavily control and inspected of all activities.

Just look after your TR and keep driving it.

Keith

[Guest ntc]

Correct and how many know the history of the car kerbs and all ?

[barkerwilliams]

Keith,

Original or modernise?

I had a friend and colleague who had knocked down and killed a child that ran out in front of him in London in the 1970’s. There were many witnesses and he was totally exonerated. Thirty five years later he was still haunted by the experience and drove really longer circuitous routes to avoid villages , schools shops etc . where there may be children.

If god forbid a child ever ran out in front of me I feel that I owe it to that child and myself to have the best braking possible on my car, which may mean modernising and improving the car. I don’t want to use the “ it’s a classic car and brakes were not so good then” type of defence. My own conscience would not believe it.

So for me original is probably best, but not braking. Brakes, & tyres need to be as good as I can make them or the car won't be on the road.

Alan

[Alec Pringle]

Hi Bruce,

 

I don't have the detail photos of those past breakages any longer - purged them only recently along with lots of other old stuff whilst downloading thousands of images from wretched Photobucket. Sod's Law that they'd get mentioned again !

 

To me the point is simply that the hubs and driveshafts were designed for 4" rims, 165 tyres and 100 or so horses.

 

They withstood the extra grunt of the 6-pot back in the day, and they've lasted decades, but nothing lasts for ever.

 

Keep feeding more power through, add bigger wheels and tyres, tube shock conversions with inadequate bump stopping, something has to give . . . . . that doesn't make the original design rubbish, current owners have way exceeded the original design parameters.

 

As for Alan's concerns about braking . . . . back in the day I could lock all four wheels at 100mph on a prodsports standard TR6. How much braking do you need ? If some damnfool child has a kamikaze moment you can't necessarily avoid it, fate is inexorable. The co-owner of my first 3A trashed our car avoiding such a child, and turned himself into a vegetable as a result. Sh*t happens.

 

Cheers,

 

Alec

[Keith66]

 

Alan

 

If you look at my second post (#24) I think you will get my general view on road safety and modern tech and I would hope that most people in the register are sensible considerate drivers who put safety high on the list of importance.

 

And our cars must be safe and legal and I’m with you on the more or less original theme as that was how it was designed to work. So no increases in power for me, nor probably any huge tyres as Alec says the suspension was not designed with those in mind.

 

But as said if there is a clear design fault or safety flaw update it and I’m with you I wouldn’t find it acceptable to use the excuse “it’s an old car the brakes don’t work very well”

 

But older cars and ours are very old will never match the safest modern cars so we have to accept that they are not the latest thing in active safety technology and drive accordingly.

 

How far can we (and every driver) go? ABS brakes were a huge safety advance and probably could be reto fitted to every car on the road with enough expenditure, so should a mandatory scrappage scheme be introduced for every non ABS car?

 

Would it then be the same with AEB? As I said it looks like it reduces rear end collisions by about 40%, the best systems even detecting pedestrians or cyclists and I for one would not even consider a new car without it. You cannot abdicate your driving responsibilities if you have these systems but each one is an additional layer of help if needed in an emergency.

 

But in terms of the TR, I’ll probably finish it’s resto as a more or less standard ’72 Pi with no extra power or go faster bits, but make sure brakes, tyres, steering, suspension or anything safety related is as good as can be.

Cheers

Keith

[jean]

I did read several sites concerning the CV halfshafts. The shafts have strict limitations with concern to their stretching and compressing and in general they accept less up and down movement of the trailing arm.

The distance between the diff flange and the brake back plate has to stay within this limits. Standard splines are in this field far more tolerant.

 

To start the car has to be placed in an precise horizontal position. This will enable you to measure the max movement the CV joint will take from bump stop to bump stop. Lightly fitted you can measure the movement in the hub threads before fitting the nut.

I'm afraid that in case of tele.shockers, which in fact deletes the lower bump stop, a new bump stop has to be added.

 

Anyhow the site from TR Nord is giving a certain amount of instructions with regard to fitting, but some of the figures are only valid for their product.

The site from Marttij O,our Finish poster, I think it's " TR6PI Garage " is also showing a comprehensive instruction guide, but it's not as simple as most think.

 

p.s. please note this is as far as I understand, but I'm not an expert...

Edited July 19, 2017 by jean

[Ragtag]

 

I'm afraid that in case of tele.shockers, which in fact deletes the lower bump stop, a new bump stop has to be added.

 

 

Hi Jean,

 

I'm not sure if I'm missing something but I run tele shocks on the rear and definitely have retained the original bump stop on the trailing arm.

[TR NIALL]

Hi Jean,

 

I'm not sure if I'm missing something but I run tele shocks on the rear and definitely have retained the original bump stop on the trailing arm.

That would depend on the Type Of Brackets used,with the more popular Bracket you need to cut off the Bumpstop as it's used as another mounting point and the Shock should have a Built In Bumpstop.

[jean]

In fact the rear suspension has 2 pump stops for the upwards/downwards travel of the trailing arm where the downwards movement is limited by the arm of the standard shock absorber and the bump stop on the chassis.

[Waldi]

Indeed Jean, which implies the stroke of the telescopic damper is (when fitted) the lower limit stop, and this does not have the soft stop of the rebound rubber that originally limits the lower travel.

So checking the travel, both ways, is important, as previously mentioned.

Waldi

[Andy Moltu]

The original hubs were not an intrinsically flawed design.

However they are now 40+ years old and metal fatigue comes into the equation.

 

This is compounded by abnormal loading such as hitting a kerb. Bigger tyres perhaps contribute to an extent but kerbing is probably more significant.

The other matter, and probably the most important is the extreme loads sometimes used to take the hubs apart when rebuilding. One or two wxtreme loads can contribute far more to metal fatigue than an almost infinite number of loads within design parameters. Once started by extreme loading then even normal use can finish off a stub axle that had been fatigued but a huge press.

[RogerH]

Hi Andy,

you raise a very interesting point (as have a couple of other posters).

The design is essentially good but is not fail safe - if it breaks you will lose the wheel.

 

But why would it break.

 

We can discount the press used during refurb' as that imparts a compressive load if done reasonably well.

The Churchill tool is completely safe.

 

If we ignore the hub flange failure shown by MS Mickey in an earlier Stag picture (not common) then we have the stub axle failure where the thread run out is.

If this had bending loads applied to it it would fail fairly quickly.

However it has a monster torque applied. This has the effect of keeping this area under a large tensile load.

The greater the torque the safer it will remain. You will never exceed its tensile strength with a nut and torque wrench.

And this will stop any bending - look at the mod' on the front hubs to add a sleeve to stiffen it all up.

 

I do not think that big tyres and Koni struts are doing the damage. The biggest forces these produce will pass through the thicker section of the stub axle.

The thread run out area will still be under a tensile load.

 

The torque load of these big tyres going sideways will impart effectively a small load compared to the materials Ultimate load so that is safe.

The griping effect of fat tyres will be a smallish load buffered by the rubber. At worst a one ton car will only add something significantly less than a ton to the Ultimate load. So there should be plenty in reserve.

 

I am not even sure that kerbing the tyre will cause a problem.

 

The ST engineers obviously did their sums and did them well.

 

So the vulnerable area is under a great tensile load and is happy. So why does it break.

These steels do not suffer normally from age hardening - unlike Ali Alloys and copper etc.

 

But; age does play a part. These steels do suffer from stress corrosion cracking - so you don;t want to get them rusty.

However over many decades atmospheric moisture gets everywhere (look at Concorde flying controls). and I believe this thread run out area is no exception.

So we have microscopic moisture living in the same place as a highly loaded section. It will go bang.

 

Does mileage have an effect.

Again I do not believe so as the mechanical structure is stable (as long as the torque loading is not reduced.

At least when the car is travelling the hub runs pretty warm and moisture is removed.

However a car left standing for twenty year may well have microscopic moisture on the hubs going no where.

 

What is the answer.

Assuming normal conditions exist the thing to get rid of is old age.

I believe there are not a lot of reports of hubs if any failing at 20 or so years.

No sure if i have heard of any at 30 years.

But TR6's have hubs that are 40 years old and there are failures.

 

There is no knowledge of mileage but they must vary from low to very high whether they fail or not.

 

So in my opinion any hub over twenty five years old (this is a lower value to give a bit of latitude) should be replaced as you will be living on borrowed time after this.

If the insurers get their act together they could easily specify that unknown or old hubs should be changed.

If ST were still in business I'm sure they would be putting out alarms and warnings.

 

 

Something to sleep on

 

Roger

Edited July 20, 2017 by RogerH

[Guest ntc]

Hi Andy,

you raise a very interesting point (as have a couple of other posters).

The design is essentially good but is not fail safe - if it breaks you will lose the wheel.

 

But why would it break.

 

We can discount the press used during refurb' as that imparts a compressive load if done reasonably well.

The Churchill tool is completely safe.

 

If we ignore the hub flange failure shown by MS Mickey in an earlier Stag picture (not common) then we have the stub axle failure where the thread run out is.

If this had bending loads applied to it it would fail fairly quickly.

However it has a monster torque applied. This has the effect of keeping this area under a large tensile load.

The greater the torque the safer it will remain. You will never exceed its tensile strength with a nut and torque wrench.

And this will stop any bending - look at the mod' on the front hubs to add a sleeve to stiffen it all up.

 

I do not think that big tyres and Koni struts are doing the damage. The biggest forces these produce will pass through the thicker section of the stub axle.

The thread run out area will still be under a tensile load.

 

The torque load of these big tyres going sideways will impart effectively a small load compared to the materials Ultimate load so that is safe.

The griping effect of fat tyres will be a smallish load buffered by the rubber. At worst a one ton car will only add something significantly less than a ton to the Ultimate load. So there should be plenty in reserve.

 

I am not even sure that kerbing the tyre will cause a problem.

 

The ST engineers obviously did their sums and did them well.

 

So the vulnerable area is under a great tensile load and is happy. So why does it break.

These steels do not suffer normally from age hardening - unlike Ali Alloys and copper etc.

 

But; age does play a part. These steels do suffer from stress corrosion cracking - so you don;t want to get them rusty.

However over many decades atmospheric moisture gets everywhere (look at Concorde flying controls). and I believe this thread run out area is no exception.

So we have microscopic moisture living in the same place as a highly loaded section. It will go bang.

 

Does mileage have an effect.

Again I do not believe so as the mechanical structure is stable (as long as the torque loading is not reduced.

At least when the car is travelling the hub runs pretty warm and moisture is removed.

However a car left standing for twenty year may well have microscopic moisture on the hubs going no where.

 

What is the answer.

Assuming normal conditions exist the thing to get rid of is old age.

I believe there are not a lot of reports of hubs if any failing at 20 or so years.

No sure if i have heard of any at 30 years.

But TR6's have hubs that are 40 years old and there are failures.

 

There is no knowledge of mileage but they must vary from low to very high whether they fail or not.

 

So in my opinion any hub over twenty five years old (this is a lower value to give a bit of latitude) should be replaced as you will be living on borrowed time after this.

If the insurers get their act together they could easily specify that unknown or old hubs should be changed.

If ST were still in business I'm sure they would be putting out alarms and warnings.

 

 

Something to sleep on

 

Roger

Hi Roger

True but most forget bent and out of balance wheels plus not running true,simple basic stuff.

[RogerH]

Hi Neil,

surprisingly, if the big nut is torqued down to the correct level then all those wobbly bits will have little effect.

 

The hub may fall off for other reasons but not due to breaking the thread run out.

 

Roger

[Tom Fremont]

Apologies if I missed this in the foregoing thread, but here are a couple more points:

 

- The standard fitment uses the same U-joint in the driveshaft as the axle shafts, but the latter see 1.725 - 1.65X the torque depending on diff ratio. One of the two applications must therefore be oversized or undersized.

 

- GOODPARTS offer either CV or uprated U-joint shafts which are apparently quite satisfactory.

 

Since I know of no suppliers of good new original design splined half-shafts I'll be going with GOODPARTS heavy duty U-joint shafts/ hubs when the time comes. The only complaint I have about the originals is that when the splines wear enough they sling around just enough to generate a low level vibration at highway speeds, undetectable unless the hardtop is on and windows tight up.

 

Cheers,

Tom

[harrytr5]

Having just come back from Classic Silverstone and the first run since fitting Classic development CV Driveshaft and hubs I could not believe how it has transformed my TR5. Much smoother and the suspension is not having a tough time now. My original uprated GKN driveshafts and Cosworth hubs which show no signs of wear can not compete with how smooth everything is now.

Just Brill.

Regards Harry TR5 Nutter